The Role of Prolactin and Testosterone on Male Paternal Care in the Common Marmoset (Callithrix jacchus)

Common marmoset fathers are actively involved in infant care and will carry infants immediately after birth. This study examined the role of prolactin and testosterone in infant responsiveness. Thirteen experienced fathers were tested postpartum outside the family with unfamiliar infant vocalizations to determine their infant responsiveness scores. Each male was examined under two conditions: 1) control and 2) lowered prolactin by cabergoline (CAB), a D2agonist. Males showed significantly lower infant response scores to unfamiliar infant vocalizations with cabergoline treatment [Wilcoxon Signed Ranks Test, Z=2.43, p=0.02]. In a subset of males from the control condition, we found that males (n=6) had significantly higher levels of testosterone in the two weeks prepartum than postpartum [t(5)2.57, p=0.04]. However, under lowered prolactin (n=4), males showed no testosterone difference pre to postpartum. We also found that pre-birth testosterone levels predicted a male’s infant response scores to unfamiliar vocalizations only in the control condition when prolactin is present. These data suggest that prolactin is involved in facilitating paternal care in the marmoset and may control the needed decrease in testosterone while parenting. This research was supported by MH070423 and RR000167.